The present invention relates to a power supplying apparatus and, more particularly, to a power supplying apparatus which reduces a rise in temperature.
A plurality of loads are connected to the power supply in an image formation apparatus such as an electronic copying machine (to be referred to as a copying machine for brevity hereinafter). The operating timings of these loads are controlled by a suitable means.
An example of such a load is a solenoid for bringing a cleaning blade into contact with and separating it from a photosensitive drum. The cleaning blade serves to scrape off residual developer (toner) on the photosensitive drum after each copying operation. The stroke of the solenoid for bringing the blade into contact with and separating it from the photosensitive drum must be about 0.5 cm. An attraction force of about 0.5 kg is required for this purpose. In order to satisfy this requirement, a solenoid has conventionally been used which has an opening rated voltage of DC 24 V and power consumption of 10 W or more.
However, if a solenoid of such a big capacity is used, the temperature inside the copying machine is raised due to heat generated by the solenoid coil.
In addition, a constant voltage power supply of a big current capacity is required to drive a solenoid of such a big capacity. In a constant voltage power supply incorporating semiconductors as switching regulators, the amount of heat generated increases with an increase in the current capacity.
Since the electrostatic latent image characteristics used in a copying machine are temperature dependent, a power supplying apparatus is desired which is capable of reducing a rise in temperature inside the copying machine to the minimum.